Modeling and simulation are increasingly being employed as tools in
the Department of Defense (DoD) to provide better insight into weapon system
performance, reduce testing and training costs, and develop force mixes
of weapon quantities and types. These uses ultimately support the twin
goals of reducing DoD weapon acquisition costs and dramatically shortening
the time to weapon system fielding. This paper briefly explores the uses
of modeling and simulation in the Predator Unmanned Aerial Vehicle (UAV)
program.

Program Background

The Predator Program is the Department's first Advanced Concept Technology
Demonstration (ACTD) to successfully demonstrate military utility. It is
now transitioning to a DoDD 5000.1 formal acquisition program. The system
provides extended range, long-dwell, near-real-time imagery intelligence
(IMINT) to satisfy reconnaissance, surveillance, and target acquisition
(RSTA) mission requirements. The Predator air vehicle carries both electro-optical/infrared
(EO/IR) and synthetic aperture radar (SAR) sensors. A Ku-band satellite
communications (SATCOM) link enables Predator to acquire imagery beyond
line-of-sight and disseminate it world-wide. The ACTD commenced on 1 January
1994 and concluded on 30 June 1996. During that period three Predator systems
were acquired. Each system consisted of three or four air vehicles, a ground
control station (GCS), a communications terminal, currently a Trojan SPIRIT
II, and ground support equipment (GSE).

In July 1995, a Predator system was deployed to Albania to support Joint
Task Force (JTF) Provide Promise. That deployment clearly demonstrated
the potential of UAVs to support military forces by monitoring civilian
activities, troop locations, artillery positions, garrison activities,
and compliance with agreements. Predator was instrumental in verifying
that Bosnians were not complying with agreements to garrison their forces.
When air forces were employed in Deliberate Force, Predator was used for
real time targeting and retargeting. As a result of the Deliberate Force
operation, Bosnian compliance was achieved and the Dayton Peace Accord
was signed by all parties.

Upon returning to CONUS in November 1995, an effort was initiated for
Predator to acquire an ice mitigation capability, which included a heated
pitot tube, ice detection sensors, and a modification to the engine air
inlets. Concurrently, an effort was initiated to develop a de-icing capability.
On 16 December 1995, US Atlantic Command, the Predator ACTD's operational
sponsor, briefed the Joint Requirements Oversight Council (JROC) and recommended
that Predator be fielded and 16 systems procured. Subsequently the JROC
recommended assignment of the Predator system to the US Air Force which
was directed by the Secretary of Defense on 9 April 1996. On 12 February
1996, the JROC stated that the Predator had demonstrated sufficient military
utility to warrant transition to production, requested that 16 systems
be fielded, and identified upgrades for consideration.

Deployed to Taszar, Hungary in mid-March 1996, the Predator system was
initially operated by the US Army. On 3 September 1996 operational command
and control was passed to the USAF ACC 11th Reconnaissance Squadron, located
at Indian Springs, NV. A detachment of personnel from that unit continues
operations of Predator in Taszar. As of 4 March 1997 there have been 189
mission flights, totaling over 1,570 flight hours by Predator within the
Bosnian area in support of Implementation Force (IFOR) and the present
Stabilization Force (SFOR) of Operation Joint Guard.

To address weather limitations, a de-icing system which dispenses ethylene
glycol over the wings was developed in 1996 and installed on two specially
configured air vehicles. In mid-November 1996, these two air vehicles were
deployed to Taszar, Hungary to be tested in European theater conditions.
Due to the worst winter in 40 years in Europe, little flying was accomplished
as prevailing weather conditions were below flight minimums. A thirty day
de-icing test at Duluth, MN is scheduled to begin in mid- March 1997.

With the demonstrated capability of Predator, Congress has been most
supportive of this UAV, increasing requested funding in both FY96 and FY97.
Currently, there is projected funding to acquire 13 Predator systems and
to develop all the pre-planned product improvement (P3I) actions required
by the JROC and ACC.

Modeling and Simulation

Modeling and simulation have been employed extensively in the Predator
ACTD. It has been used in the broadest context to address 'global issues'
such as force mix assessments, in a lesser context to simulate capabilities
in exercises, and in an even more narrow context to address specific performance
issues such as identification of design trade-off parameters.

At the highest levels, modeling and simulation are being used to develop
assessments of alternative force mixes of manned and unmanned reconnaissance
systems, including Predator. Several classified studies, such as the Intelligence,
Surveillance, and Reconnaissance (ISR) Joint Warfighting Capability Assessment
(JWCA), and the Command, Control, Communications, and Computers ISR Mission
Assessment (CMA) are using modeling and simulation to identify reconnaissance
architecture options for JROC/CINC considerations. Additionally the DARO
Architecture Development includes within its force mix considerations of
all UAVs including Predator. Predator has been integrated into each of
the exercises and its performance characteristics (platform and sensors)
are incorporated in the full range of studies which include campaign and
mission level analyses. Results of these efforts are assisting in the determination,
for example, of the number of Predator UAV systems that will be needed
to support the objective of "dominant battlespace awareness"
at an affordable cost.

At the next level, modeling and simulation are being used to support
Predator participation in operational exercises. In these exercises, "virtual"
Predators are flown by operational users because the limited quantities
of real hardware assets are unavailable and because modeling and simulation
yields substantive insights at considerably lower cost than operating the
real assets. These exercises have contributed significantly to the development
of the concepts of operation (CONOPS) for Predator and to an increase in
the user knowledge base about the employment of UAVs in general. For instance,
in FY96 Predator was modeled in a simulation called MUSE, the Multiple
Unmanned Aerial Vehicle Simulation Environment, which was used in a Republic
of Korea/US Combined Forces and US Forces, Korea exercise called Ulchi
Focus Lens 96. The MUSE was combined with an improved Joint Surveillance
and Target Attack Radar System (JSTARS) simulation to provide a representation
of real-time capabilities at selected theater, corps, and division level
command and control headquarters. The simulations also demonstrated the
tremendous challenge facing operational user staffs in synchronizing real-time
imagery assets with battlefield operations. The US Army's III Corps has
also used MUSE to do predictive simulations of Predator for its Corps-level
Command Post Exercise (CPX) to test new CONOPS prior to live exercises
in the field. MUSE was employed in February 1997 during III Corps UAV exercise
ramp-up in preparation for the Force XXI's Advanced Warfighting Exercise
(AWE) to be held at the National Training Center at Fort Irwin, CA beginning
in mid-March 1997.

At a third level, modeling and simulation have been used in the Predator
program to assess operational performance, analyze performance parameters,
conduct tradeoffs, and evaluate potential system changes and improvements.
Examples include:

While Predator was initially staged at Fort Huachuca, AZ for development
and training, the Naval Air Warfare Center, Weapons Division, China Lake,
CA conducted initial radar cross section (RCS) measurements of the Predator
air vehicle. Modeling was then used to make a determination of the Predator
RCS.

In accomplishing the initial operational assessment of Predator, the
Air Force Operational Test and Evaluation Center (AFOTEC) employed several
engineering models and conducted numerous simulations using Predator data
collected by the Defense Evaluation and Support Activity (DESA) during
the 1995 European deployment. The results were helpful in affirming several
of AFOTEC's conclusions about Predator's effectiveness as the European
field data was limited. On many occasions sufficient field data simply
cannot be collected to validate critical assessment objectives and modeling
and simulation are the only practical alternative for evaluation.

Much of the engineering design of the Predator de-icing system was
done through modeling and simulation. The determination of ethylene glycol
flow requirements, hole emplacement on the front leading edge of the wings,
and the flow rates necessary to operate successfully were modeled and then
tested in a wind tunnel prior to actual vehicle flight tests which are
still ongoing. If the modeling and simulation had not been available, both
the time and cost of the development of the de-icing system would have
been negatively impacted.

A recently completed modeling and simulation study for the DoD's Director
of Operational Test and Evaluation (DOT&E) has been used to predict
the target area of coverage capabilities of the Predator system. This work
was done to gain insight into Predator's ability to meet its Key Performance
Parameter (KPP) of "continuous 24-hour target area presence."
As demonstration of this capability has never been attempted, an event-driven
simulation was developed to help identify factors that might affect Predator's
ability to meet this requirement. The model assumed the four air vehicle,
Air Force Predator system being tasked to maintain continuous coverage
at various ranges. Failures affecting the mission were injected into the
simulation based on ACTD-derived performance data and projected system
reliability. System reliability was defined in terms of mean time between
mission affecting failures (MTBMAF). Noncritcal scheduled and unscheduled
maintenance actions were also introduced. Maintenance capability was defined
in terms of the number of parallel repair paths available to complete a
maintenance action. The greater the number of parallel repair paths available,
the less likely were failed systems to wait for repairs. The study's
key finding was that the Predator's ability to continuously monitor a target
area, (i.e. target area presence or time on station), is most sensitive
to the transit time to the target area and less sensitive to system reliability
and maintenance capability. This is because lengthy transit times imply
a lesser proportion of total vehicle flying hours available for target
area presence. For the assumptions used in the study, this effect had a
greater impact on target area presence than other factors. See attached
Figures 1 and 2. This simulation will be used to
support the Predator system's operational test and evaluation which should
reduce both the cost and time of the testing.

Conclusions

The Predator UAV program, as an ACTD, is an example of acquisition reform
in action. The judicious use of creative modeling and simulation has directly
contributed to managing costs in all aspects of the ACTD by predicting
operational effectiveness in conjunction with abbreviated operational assessments,
assessing air vehicle survivability cost-effectively, determining optimum
system configuration, and assessing alternative force structure options.